�Typhus, cholera, dysentery. and what was called "ship fever" -- in the mistaken belief that shipboard conditions caused the epidemics -- were the great killers. We now know -- and medical authorities at midcentury� were beginning to realize -- that these diseases did not originate at sea but were brought aboard by either passengers or crew. Once aboard the conditions on the crowded and unsanitary ships were ideal for the propagation of disease. In the famine year of 1847 -- the worst year in terms of mortality -- perhaps 100,000 men, women, and children embarked for Canada from British ports. Some 17,000 died at sea and another 20,000 died of disease after landing, mostly along the shores of the St. Lawrence. At just one place, the quarantine station at Grosse Isle off Quebec City, between mid- May and early November 1847,� 8691 persons were admitted to a hospital whose normal capacity was 200; 3,228 died.� Conditions at Grosse Isle defy description; during the latter half of 1847 "only" 850 of� the 7000 admitted to New York's new quarantine hospital died. Nor did the horrors end in 1847. Kerby Miller estimates that in the cholera year of 1853, 10 percent of the 180,000 Irish emigrants died at sea.�

�All told, in the famine years something more than two million Irish went overseas. Most of them, nearly a million and a half, came to the United States; a third of a million went to Canada, and many of those came sooner or later to the United States; perhaps a quarter of a million settled in Britain, and thousands of others went to Australia and elsewhere. The total emigration was about a quarter of the prefamine population. More people left Ireland in the eleven years 1845-55 than in its previous recorded history.�

�Almost all historians writing about the American Irish agree that the famine years left enduring scars on the Irish and on Irish American psyches, exacerbating, in many ways, attitudes that were already there. ...�